Valves operated by their own medium have long been known in the prior art. A typical valve of the type indicated above is described in DE-OS 36 42 669 A1. The valve described in the above publication comprises an electromagnetic control actuator, the armature of which, which is surrounded by a coil, closes off the relief bore in the rest state and frees it on actuation of the control actuator.
In valves of the above type, the hysteresis behaviour of the electromagnetic control actuator is regularly a problem, which during operation leads to a change in the positioning accuracy of the control actuator, with the result that the opening and closing behavior of the valve is no longer completely controllable. A further disadvantage of such valves is that the electromagnetic control actuator that is used significantly increases the weight of the valve structure and the space required thereby.